Bottomfish Gear Calibration

Bottomfish Gear Calibration

Pacific Islands Fisheries Group (PIFG) recently completed its third bottomfish gear calibration research study off of Maui. The Maui Gear Calibration Cruise ran from April 15 to 29, 2013. This was the first cruise where the four treatments have been simultaneously deployed – BotCam, SeaBED AUV, Active Acoustics, and PIFG Research Fishing. The vessels were able to fish 10 sampling days covering 151 grids.

PIFG worked with the NOAA Pacific Islands Fisheries Science Center (PIFSC) through a Cooperative Research Project Grant to assess Hawaii’s bottomfish fishery. The purpose of this research was to gather data to develop fishery independent sampling protocols to help monitor Hawaii’s bottomfish population.

In addition to providing the commercial fishing effort, the fishermen assisted by tagging 200 fish from the Deep 7 complex of species, and contributed to the collection of bio samples for life history studies. The life history study is essential in determining age, size, and time (season) of maturity for each managed species. This information is critical for fisheries assessment and future management decisions.

During the recent Maui study PIFG coordinated data collection was done using commercial bottomfish fishermen along with trained PIFG observers. The observers collected important fishing information such as location, wind speed and direction, current speed and direction, start and end time of each line dropped, bait, and catch depredation. These are the types of conditions and factors that can make or break a typical bottomfish trip involving the local fleet of small fishing vessels. All fish caught were identified and measured and all deep 7 species caught were retained for bio sampling.

For sampling purposes during this trip each vessel was instructed to fish a pre-assigned gridded area for a predetermined amount of time each day. Commercial vessels fished alongside R/V Hukipono which dropped a Botcam (bottom tethered camera) to video the presence of fish in the area (limited to camera field of view). Botcam provides video of fish that may or may not bite or are not specifically targeted by fishermen. This technology is limited by light (daylight dependant) and water clarity in the area it is dropped.

The third and most sophisticated gear is theAcoustic Beam gear which is mounted and operated from the R/V Oscar Sette. The Acoustic Gear is like a huge sensitive fish finder that scans the water column for the presence of fish or marine life. The advantage of this gear is that it can cover a large amount of area in a short period of time. Repeated passes over an area during a length of time (day & night) has shown interesting fish habits. During the day certain species seem to gather into vertical formations then disperse horizontally during the night. What triggers this behavior and activity is yet to be determined. The third and most sophisticated gear is the Acoustic Beam gear which is mounted and operated from the R/V Oscar Sette. The Acoustic Gear is like a huge sensitive fish finder that scans the water column for the presence of fish or marine life. The advantage of this gear is that it can cover a large amount of area in a short period of time. Repeated passes over an area during a length of time (day & night) has shown interesting fish habits. During the day certain species seem to gather into vertical formations then disperse horizontally during the night. What triggers this behavior and activity is yet to be determined.

Having 3 fishing vessels, the Botcam research vessel, and a 224 foot research ship operating in the same area (approximately 2 miles by 4 miles) all at one time was essential and could have been perilous at times.